There are various types of power distribution devices used in vehicle electrical systems, some of these devices are referred to as power distribution boxes, electrical connection boxes, power centers, etc. A power distribution device distributes low voltage battery power to various accessories and devices within a vehicle electrical system. In many traditional power distribution device designs, the device includes a relay block having a large number of cavities that differ in terms of size and shape and accommodate various relays, fuses and other serviceable electric devices.
An example of such a relay block can be seen in FIGS. 1-3, where the relay block 10 is molded from an insulating plastic material and includes various cavities or wells 20, 26, 30 designed to accommodate different types of electrical components. For example, cavities 20 are designed to receive smaller relays 22, whereas some of the other larger or deeper cavities 26, 30 may accommodate electric components of different sizes and shapes, like certain high current fuses 28 or other serviceable electric components 32. In general, the relay block 10 is configured so that once the electric components 22, 28, 32 are inserted and installed within the relay block, the top surfaces of the components are aligned and generally terminate in a common plane x′. Such a configuration, referred to herein as a “component aligned design,” can make manufacturing a corresponding cover quite easy, as the cover can simply be a flat housing that closely fits over the relay block 10 such that it is in close proximity to the top surfaces of the electric components 22, 28, 32 which are in a common plane x′. A potential drawback, however, to a component aligned design like this is that it increases the average height H′ of the relay block 10.
To explain, consider the three different sections or portions 40-44 of the relay block 10 that are illustrated in FIG. 3. The section 40 includes a number of smaller size cavities 20 that accommodate relays 22 which are smaller than the fuses 28. The section 42, on the other hand, includes a number of medium size cavities 26 that are deeper than cavities 20 and receive fuses 28, which are taller than relays 22. The tops or openings to cavities 26 could be on the same plane as those of cavities 20, but then the upper surfaces of fuses 28 would not be aligned with the upper surfaces of relays 22 in a common plane, as is required with “component aligned designs.” The section 44 includes a deep cavity 30 in order to accommodate a large serviceable electric component 32 which protrudes out of the upper surface. Despite the electric components 22, 28, 32 having varying heights, all of their top surfaces generally terminate in a common plane x′ due to the staggered cavity nature of a component aligned design, which is intentional. The component aligned design is certain advantages, but it does tend to increase the overall height H′ of the relay block 10.
Those skilled in the art will appreciate that due to packaging and other dimensional constraints, as well as efforts to reduce the overall weight and cost of vehicle components, it may be desirable to provide a relay block for a power distribution device that has a reduced average height.